Paper EM-TuP28
Quantum Effects Produced by Silicon Nanoparticles Embedded in Stacks of Silicon Rich Oxide Obtained by Low Pressure Chemical Vapor Deposition

Tuesday, November 11, 2014, 6:30 pm, Room Hall D

Currently, new electronic and optoelectronic applications are using stacked arrays of different films, like superlattices, multilayers, tandem solar cells, etc. This work shows results and discussion of the structural and electrical properties from stacks of silicon rich oxide (SRO) films with different silicon excess. SRO films were deposited on n-type silicon (Si) substrate with low resistivity (2~3 Ω•cm) using the low pressure chemical vapor deposition (LPCVD) technique. Two different stacks of SRO (SSRO) were formed varying the flow ratio (Ro) between N₂O and SiH₄ with Ro=10 (SRO₁₀) and Ro=30 (SRO₃₀). Also, low and high Si-implantation, 5x10¹⁵ and 2x10¹⁶ at/cm² doses respectively, were applied to SSRO. A thermal annealing was applied to all SSRO at 1100°C for 3 hours. Metal-oxide-semiconductor (MOS) structures were fabricated using the SSRO as dielectric layer with Aluminium (Al) on top and back contacts obtained by thermal evaporation. Cross section images of the Al/SSRO/Si structures were obtained by Transmission Electron Microscopy (TEM). The thickness of SSRO and diameters of embedded Si-nanoparticles (Si-Np’s) were calculated from TEM images. The Si-implantation increases the size and density of Si-Np’s in the SSRO. Current vs. Voltage (I–V) measurements of the Al/SSRO/Si structures showed current oscillations, staircases and bumps at room temperature. High frequency Capacitance vs. Voltage (C–V) measurements exhibited little jumps in the accumulation region due to charge trapping and de-trapping effect produced by the presence of Si-nPs. A group of SSRO structures showed a large hysteresis related to traps density in the SRO₁₀ films. The current oscillations and the other anomalies from electrical characterization were related with quantum effects like tunneling and Coulomb blockade between on and off states of the conductive paths as a result of Si-nPs embedded in the SSRO.